"A Trim" on Speed Density?

[txstang84]

A map clamp (aka voltage clamp) will stop the computer from seeing the boost provided by the blower. Get that and a rising rate fuel pressure regulator and you should be set. The RRFPR will increase fuel pressure based on the amount of boost it reads. You can set it up to do a 5:1 ratio (5psi of more fuel pressure per 1psi of boost) or whatever suits your application. This works fine for mild setups but you really dont want to use this when going for big power because more than 120psi or so of fuel pressure is just to much. Also, watch out with putting hot cams in speed density cars because they cause you to loose massive amounts of vaccuum @ idle which in turn causes the cars to run very rich when idling. Hope this helps.

i was sure i'd read somewhere that anymore than 70-75psi on stock style injectors was enough to cause them to not flow properly and burn up the coil quicker due to the high effort req'd to open the pintle? anyone have any good data on this one?

 

[Rick 91GT]

Over 90% is pushing it, they have a tendency to stick open...then they are trash. It is best to keep them around 80-85% duty cycle...

 

[txstang84]

...i've read a little bit from fordfueljection.com about duty cycle, but how exactly do you determine that? or do you have to hook your car up to a datalogger during a dyno run?

 

[tmoss]

Brainstorm (?) - You should be able to get a VERY close idea by monitoring peak voltage at one of the injectors. 12vdc = 100% duty cycle, 90% = 10.8vdc, 80% = 9.6vdc. Most good multimeters today have a "peak hold" feature that might be able to be used by connecting it to an injector with pins through the wire like you do for the TPS (the meters are very high input impedance, so no ill effects to injector applied voltage would occur). No need to buy a TwEECer or other tuning hardware/software. The peak voltage would be the highest value (highest duty cycle) seen at the injector.

 

[iblue]

i was sure i'd read somewhere that anymore than 70-75psi on stock style injectors was enough to cause them to not flow properly and burn up the coil quicker due to the high effort req'd to open the pintle? anyone have any good data on this one?

Ive known guys who have ran 24lb/hr injectors out of the NA cobra's in their turbo neons with max fuel pressure of 100-110psi for 20k+ miles without issue. I don't know how it does in the longer run. But I would completely agree that is is not the optimum way to do this. Ultimately you would want complete control over fuel and to adjust duty cycle based on airflow but for that you should just go to a mass air setup.

 

[352Ford2]

mistake